;;   <http://www.netscape.com/newsref/std/cookie_spec.html>

;; (declare (unit cookie))

(module cookie
    *

(import chicken scheme data-structures extras srfi-13 ports posix)
(import (chicken base) scheme queues srfi-13 (chicken port) (chicken io)(chicken file) (chicken format) (chicken string) (chicken time posix))
  
(require-extension srfi-1 srfi-13 srfi-14 regex)
;; (use  srfi-1 srfi-13 srfi-14 regex)
;; (declare (export parse-cookie-string construct-cookie-string))

;; #>
;; #include <time.h>

;; stml is a list of html strings

;; (declare (unit stml))

(module stml2
    *

(import chicken scheme data-structures extras srfi-13 ports posix srfi-69 files srfi-1) 
(import (chicken random) (chicken base) (chicken string) (chicken time) scheme queues srfi-13 (chicken port) (chicken io) (chicken file) srfi-69 srfi-1 (chicken condition) (chicken time posix) (chicken process-context posix) (chicken pathname) (chicken blob) (chicken format) (chicken process) (chicken process-context)) 

(import cookie)
(use cookie (prefix dbi dbi:) (prefix crypt c:) typed-records)
(import (prefix dbi dbi:) (prefix crypt c:) typed-records)

;; (declare (uses misc-stml))
(use regex)
(import regex)

;; The (usually global) sdat contains everything about the session
;;
(defstruct sdat
  ;; database
  (dbtype 'pg)
  (dbinit #f)

;; to obscure and indirect database ids use one time keys
;;
;;  (s:get-key 'n 1)     => "n99e1882" n=number 99e is the week number since 1970, remainder is random
;;  (s:key->val "n1882") => 1
;;
;;  first letter is a type: n=number, s=string, b=boolean
(define (s:get-key key-type val)
  (let ((mkrandstr (lambda (innum)(number->string (random innum) 16)))
  (let ((mkrandstr (lambda (innum)(number->string (pseudo-random-integer innum) 16)))
	(week      (number->string (quotient (current-seconds) (* 7 24 60 60)) 16)))
    (let loop ((siz 1000)
	       (key (conc key-type week (mkrandstr 100)))
	       (num 0))
      (if (s:session-var-get key) ;; have a collision
	  (loop (cond                 ;; in the unlikey event we have trouble getting a new var, keep increasing the size of the number
		 ((< num 50)  100)

#;(define session:valid-chars "abcdefghijklmnopqrstuvwxyz0123456789") ;; cookies are case insensitive.
#;(define session:num-valid-chars (string-length session:valid-chars))

#;(define (session:get-nth-char nth)
  (substring session:valid-chars nth  (+ nth 1)))

#;(define (session:get-rand-char)
  (session:get-nth-char (random session:num-valid-chars)))
  (session:get-nth-char (pseudo-random-integer session:num-valid-chars)))

#;(define (session:make-rand-string len)
  (let loop ((res "")
             (n   1))
    (if (> n len) res
        (loop (string-append res (session:get-rand-char))
              (+ n 1)))))

;; maybe replace above make-rand-string with this someday?
;;
#;(define (session:generic-make-rand-string len seed-string)
  (let ((num-chars (string-length seed-string)))
    (let loop ((res "")
	       (n   1))
      (let ((char-num (random num-chars)))
      (let ((char-num (pseudo-random-integer num-chars)))
	(if (> n len) res
	    (loop (string-append res (substring seed-string char-num (+ char-num 1)))
		  (+ n 1)))))))

;; Rely on crypt egg's default settings being secure enough, accept
;; backwards-compatible OpenSSL crypt passwords too.
;;

(define session:valid-chars "abcdefghijklmnopqrstuvwxyz0123456789") ;; cookies are case insensitive.
(define session:num-valid-chars (string-length session:valid-chars))

(define (session:get-nth-char nth)
  (substring session:valid-chars nth  (+ nth 1)))

(define (session:get-rand-char)
  (session:get-nth-char (random session:num-valid-chars)))
  (session:get-nth-char (pseudo-random-integer session:num-valid-chars)))

(define (session:make-rand-string len)
  (let loop ((res "")
             (n   1))
    (if (> n len) res
        (loop (string-append res (session:get-rand-char))
              (+ n 1)))))

;; maybe replace above make-rand-string with this someday?
;;
(define (session:generic-make-rand-string len seed-string)
  (let ((num-chars (string-length seed-string)))
    (let loop ((res "")
	       (n   1))
      (let ((char-num (random num-chars)))
      (let ((char-num (pseudo-random-integer num-chars)))
	(if (> n len) res
	    (loop (string-append res (substring seed-string char-num (+ char-num 1)))
		  (+ n 1)))))))


;;======================================================================
;; P A R A M S

      (if debugmode (session:log self "session:setup dbfname=" dbfname ", dbtype=" dbtype ", dbinit=" dbinit))
      (if (eq? dbtype 'sqlite3)
	  ;; The 'auto method will distribute dbs across the disk using hash
	  ;; of user host and user. TODO
	  ;; (if (eq? dbfname 'auto) ;; This is the auto assignment of a db based on hash of IP
	  (let ((dbpath (pathname-directory dbfname)))  ;; do a couple sanity checks here to make setting up easier
	    (if debugmode (session:log self "INFO: setting up for sqlite3 db access to " dbfname))
	    (if (not (file-write-access? dbpath))
	    (if (not (file-writable? dbpath))
		(session:log self "WARNING: Cannot write to " dbpath)
		(if debugmode (session:log self "INFO: " dbpath " is writeable")))
	    (if (file-exists? dbfname)
		(begin
		  ;; (session:log self "setting dbexists to #t")
		  (set! dbexists #t))))
	  (if debugmode (session:log self "INFO: setting up for pg db access to account info " dbinit)))